1. Field of the Invention
The present invention relates to a fuel cap for opening/closing a filler opening of a fuel tank of a vehicle, and particularly, to a vehicle fuel cap where static charge in a human body is earthed through the fuel cap.
2. Description of the Related Art
Conventionally, a vehicle fuel cap is known as disclosed in paragraphs 0052 to 0063 and FIGS. 1, 11, 16 32, and 33 of Japanese Patent No. 3389850 (hereinafter referred to as patent document 1).
FIGS. 6A and 6B are drawings showing a conventional vehicle fuel cap: FIG. 6A is a perspective drawing of a lid of the fuel cap; FIG. 6B is a half-section drawing of the fuel cap.
As shown in FIG. 6B, a conventional vehicle fuel cap 100 is designed to form a lid 200 having a gripper 210, which a fuel filling person grips, of a conductive resin member, to make a discharge projection 220 of the lid 200 come near a filler neck 300 made of steel, and thereby to discharge static charged in a human body. In other words, when the fuel filling person grips the lid 200 in opening/closing a filler opening 310 of the filler neck 300, the conventional vehicle fuel cap 100 earths the static charge in the human body from the lid 200 to the filler neck 300 and through a bracket (not shown) to a vehicle body side, and prevents a spark from being discharged within the filler opening 310 and a discomfort by the static (for example, see the patent document 1).
The discharge projection 220 consists of sheet-form projection pieces projected toward a center side from four places of an inner wall 240 of an opening end of the lid 200. Between the discharge projection 220 and the filler neck 300 is set a gap L1 consisting of a discharge distance of not more than 1 mm in order to be able to obtain a mild discharge characteristic.
The gap L1 is preferably not more than 0.65 mm and comparatively demands an accuracy. When the gap L1 is too large, it becomes difficult to discharge (earth) static.
On the other hand, when there is no gap L1 and the fuel cap 100 is attached to/detached from the filler neck 300 in a state of the lid 200 and the filler neck 300 making contact, a feeling is generated in rotating and fastening the fuel cap 100 because a friction resistance occurs by the lid 200 and the filler neck 300 making contact and a desired fastening force (axial force) of the fuel cap is not obtained. In addition, in this case the lid 200 and the filler neck 300 make contact and wear, thereby a surface treatment film is lost, and a rust also sometimes occurs.
Consequently, in the conventional fuel cap 100, in order to eliminate the problems and improve the accuracy of the gap L1, a slit 230 for preventing a surface sink in injection molding is formed in a vicinity of the discharge projection 220 of the lid 200.
However, in the fuel cap 100 of the patent document 1 the slit 230 is formed long at an outer peripheral portion of the lid 200, so there is a problem of an appearance being bad because the slit 230 is within a view of a fuel filling person when he/she opens/closes the filler opening 310 by the fuel cap 100.
In addition, the slit 230 is approximately same in length in a center-line direction of the fuel cap 100 as the discharge projection 220 and is formed comparatively long. Accordingly, there is a problem that a dust and the like invade into the fuel cap 100 from one of the slits 230.
Consequently, a vehicle fuel cap is strongly requested that reduces a dust invasion and has a good appearance.